Positive displacement pump



FIG. 1 is a perspective view of a positive displacement pump showing ournew design;

FIG. 2 is an elevational view taken from one end thereof.

FIG. 3 is an elevational view taken from one side thereof.

FIG. 4 is an elevational view taken from the end opposite that in FIG.2.

FIG. 5 is a perspective view of a modified form of the positivedisplacement pump shown in FIG. 1.

FIG. 6 is an elevational view taken from one side of FIG. 5.

FIG. 7 is an elevational view taken from one end of FIG. 5.

FIG. 8 is an elevational view taken from the end opposite that shown inFIG. 7.

The ornamental design for a "positive displacement pump", substantially as shown and described. 